This invention relates to oxidatively curable coating compositions containing polyether alcohols which are; the reaction product of 3,4-epoxy-1-butene and optionally a saturated oxirane, initiated with water or an alcohol. The invention also relates to oxidatively cured films formed from the coating compositions.
Recently, intense research efforts in the coating industry have been directed to reducing volatile organic compounds (VOCs) in coating formulations due to environmental concern and governmental regulation. One of the emerging technologies developed for this purpose is to use reactive diluents in coating formulations. A typical reactive diluent has a viscosity which is low enough to enable it to function as an organic solvent although it remains in the films when the coatings are cured. In order to achieve that and achieve optimum coating properties, a reactive diluent needs to be a non-volatile liquid under the curing condition and should have a functionality which allows it to participate in the curing process. Accordingly, a non-volatile liquid at room temperature with allyl functionality would be desirable as a reactive diluent for oxidatively curable coatings.
In a paper presented at the 65th Annual Meeting of the Federation of Societies for Coatings Technology (October 1987) by J. W. Kilapczyk of Monsanto, and published in the Journal of Coatings Technology, vol. 60, no. 756, p. 63, 1988, it was reported that poly(allyl glycidyl ether) resins significantly accelerate the curing of thin acrylate and methacrylate films at low temperature in air and under practical anaerobic conditions.
In J.M.S.-Pure Appl. Chem., A33 (4), p.509 (1996) it was reported that lacquers obtained from an alkyd resin containing 10-16 weight % of glycerol allyl ether exhibit short drying time, good hardness of coatings, and good water resistance. In J. Appl. Polym. Sci., 70, 2031 (1998) it was also reported that high hardness of coatings cured in air using photoinitiators can be achieved for an unsaturated polyester resin with polyfunctional allyl ether monomers incorporated into polyester molecules as the end groups or as the pendant geminal groups.
Poly(allyl ethers) derived from polyols and carbohydrates, particularly allylated pentaerythritol, trimethylolpropane, and starches and sugars have been widely investigated as monomers suitable for protective coatings. These materials are attractive since they undergo autoxidative polymerization in contact with air. However, because of slow curing rates, color formation, high cost, and relatively poor substrate bonding strength, films of these allyl ethers have limited commercial use (see Allyl Compounds and Their Polymers by C. E. Schildknecht, Wiley Interscience, 1973).
Accordingly, it is an object of the present invention to overcome the above deficiencies and to provide oxidatively curable, low cost, allylic polyethers that are fast curing, have superior coating properties and which provide films having good hardness and high resistance to chemical attack.
The invention relates to oxidatively curable coating compositions containing an EpB polyether alcohol or a derivative thereof, which is a reaction product of 3,4-epoxy-1-butene and optionally a saturated oxirane compound, initiated with water or an alcohol. The coating compositions may contain other curable resins such that the EpB polyether alcohol functions as a reactive diluent. Alternatively, the EpB polyether alcohol can function as the main film-former in the oxidatively curable coating composition. The coating compositions containing EpB polyether alcohols cure oxidatively, preferably with commercially available metal driers.
The invention also relates to an EpB polyether alcohol or a derivative thereof, which is the reaction product of 3,4-epoxy-1-butene and a saturated oxirane compound, initiated with water or an alcohol. It is not necessary to react an alk-1-enyloxy oxirane such as those disclosed in U.S. Pat. No. 5,200,437 to Dougherty et al. to make the oxidatively curable EpB polyether alcohols of the invention. These alk-1-enyloxy oxiranes are costly and cannot be incorporated using acid catalysis due to the sensitivity of the vinyl ether group towards acid. These EpB polyether alcohols can function as reactive diluents in oxidatively curable coating compositions. In addition, these EpB polyether alcohols can function as a coating resin alone without other curable resins. The EpB polyether alcohols are also useful as surfactants, resins, chain extenders, monomers, or as an additive for various oxidatively curable coating systems including alkyds, unsaturated polyesters, acrylates, epoxies, urethanes, and latex polymers. The EpB polyether alcohols cure oxidatively, using commercially available metal driers.
One embodiment of the invention provides an oxidatively curable coating composition comprising (a) about 5-100 weight % of an oxidatively curable EpB polyether alcohol or a derivative thereof, (b) about 0-95 weight % of a curable resin, (c) about 0-40 weight % of an organic solvent, and (d) a catalytic amount of a metal drier. The EpB polyether alcohol is a reaction product of: (i) 3,4-epoxy-1-butene and (ii) an initiator selected which is water or an alcohol. The EpB polyether alcohol contains n units of residue (I) and m units of residue (II). 
The sum of (n+m) is about 1 to 70 and the ratio of n/(n+m) is a value in the range of about 0.70 to 1.00.
In another embodiment of the invention, there is provided an EpB polyether alcohol which is a reaction product of: (a) 3,4-epoxy-1-butene, (b) a saturated oxirane compound; and (c) an initiator which is water or alcohol. The reactants used to make the EpB polyether alcohol which contains a saturated oxirane compound do not include an alk-1-enyloxy oxirane. The EpB polyether alcohol contains n units of residue (I) and m units of residue (II) shown above. The sum of n+m is about 2 to 70 and the ratio of n/(n+m) is a value in the range of about 0.70 to 0.95.
In a third embodiment of the invention, there is provided an oxidatively curable coating composition which contains:(a) about 5-100 weight % of an oxidatively curable polyether alcohol or derivative thereof; (b) about 0-95 weight % of a curable resin; (c) about 0-40 weight % of an organic solvent; and (d) a catalytic amount of a metal drier. The EpB polyether alcohol is a reaction product of:(i) 3,4-epoxy-1-butene: (ii) a saturated oxirane compound and (iii) an initiator which is water or an alcohol. The polyether alcohol contains n units of residue (I) and m units of residue (II) as shown above, wherein the sum of n+m is about 1 to 70 and the ratio of n/(n+m) is a value in the range of about 0.70 to 1.00.
A fourth embodiment of the invention provides a polyether alcohol which is a block copolymer formed by reacting (i) 3,4-epoxy-1-butene, (ii) a saturated oxirane compound, and (iii) an initiator which is water or an alcohol, with the proviso that the reactants do not include an alk-1-enyloxy oxirane. The block copolymer contains n units of residue (I) and m units of residue (II) shown above, wherein the sum of n+m is a value in the range of about 1 to 70 and the ratio of n/(n+m) is a value in the range of about 0.70 to 1.00.
A fifth embodiment of the invention relates to an oxidatively cured film of the oxidatively curable coating composition containing an EpB polyether alcohol which is a reaction product of: 3,4-epoxy-1-butene and an initiator which is water or an alcohol as described above.
A sixth embodiment of the invention relates to an oxidatively cured film of the oxidatively curable coating composition containing an EpB polyether alcohol which is a reaction product of: 3,4-epoxy-1-butene, a saturated oxirane compound, and an initiator which is water or an alcohol as described above.
A seventh embodiment of the invention provides a composition comprising (a) an oxidatively curable EpB polyether alcohol which is a reaction product of 3,4-epoxy-1-butene and a saturated oxirane compound, initiated with water or an alcohol, with the proviso that the reactants do not include an alk-1-enyloxy oxirane described above, (b) a surfactant; and (c) water. The EpB polyether alcohol comprises n units of residue (I) and m units of residue (II) shown above, wherein the total value of n+m is about 2 to 70 and n/(n+m) is a value in the range of about 0.70 to 0.95.
As discussed above, one aspect of the invention relates to oxidatively curable coating compositions containing an EpB polyether alcohol or a derivative thereof, which is a reaction product of 3,4-epoxy-1-butene and optionally a saturated oxirane compound, initiated with water or an alcohol. The coating compositions may contain other curable resins such that the EpB polyether alcohol functions as a reactive diluent. Alternatively, the EpB polyether alcohol can function as the main film-former in the oxidatively curable coating composition. The coating compositions containing EpB polyether alcohols cure oxidatively, preferably with commercially available metal driers.
The EpB polyether alcohol which is a reaction product of 3,4-epoxy-1-butene and optionally a saturated oxirane compound, initiated with water or an alcohol, contains n units of residue (I) and m units of residue (II). 
The sum of (n+m) in the EpB polyether alcohols is a value in the range of about 1 to 70 and n/(n+m) is a value in the range of about 0.70 to 1.00.
Advantageously, polyether alcohols which are the reaction product of 3,4-epoxy-1-butene and optionally a saturated oxirane compound, initiated with water or an alcohol can function as oxidatively curable coatings or as reactive diluents in oxidatively curable coatings. The phrase oxidatively curable refers to the ability of the polyether alcohols to cure in air, either at room temperature or at elevated temperatures, in the presence of metal driers. The phrase curable resin refers to a resin which is capable of being cured by any means, including but not limited to oxidatively curable resins.
The EpB polyether alcohols may be prepared by the polymerization of 3,4-epoxy-1-butene, and optionally a saturated oxirane compound, initiated with water or an alcohol. The alcohol which is used to initiate the polymerization may be selected from a vast number and broad variety of monohydric alcohols and polyhydric alcohols. Because the polyether alcohol grows from the hydroxyl group of the alcohol, ROH or polyol, R(OH)x, where X is the number of hydroxyl groups, the xe2x80x9cRxe2x80x9d group may be the terminal residue of the alcohol. As discussed below this residue of the alcohol may be a major or minor component of the polyether alcohol.
Suitable monohydric alcohol initiators include low molecular weight organic alcohols and polymeric alcohols which may be linear or branched chain, aliphatic, alicyclic, or aromatic. Monohydric alcohol initiators preferably are selected from alkanols containing up to about 20 carbon atoms. When a monohydric alcohol, R4H, is used as the initiator, the polyether alcohol product obtained has a primary hydroxyl group on one end of the polymer chain and thus is a polymeric alcohol. The other end of the polymer chain is terminated with the residue of the alcohol initiator, e.g., a residue having the formula xe2x80x94R4 wherein R4 is the residue of an alcohol, preferably an alkyl group, containing up to about 20 carbon atoms. Although secondary or tertiary alcohols may be used, primary alcohols are preferred. Some typically useful monohydric alcohol initiators include methanol, ethanol, n-butanol, isobutanol, 2-ethylhexanol, n-decanol, stearyl alcohol, cetyl alcohol, allyl alcohol, benzyl alcohol, methoxypolyethylene glycol, phenol, cresol and the like. Monohydric alcohols having from 1 to 20 carbon atoms are the preferred monohydric alcohols initiators. More preferred monhydric alcohols are those having from 1 to 12 carbon atoms.
Polyhydric alcohol initiators contain 2 or more hydroxyl groups and may be monomeric or polymeric compounds. Examples of the polyhydric alcohol initiators include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2,2-dimethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, 2-butene-1,4-diol, 1-butene-3,4-diol, hydroquinone, resorcinol, bis-phenol-A, glycerol, trimethylolpropane, starch, sucrose, glucose, pentaerythritol, polyethylene glycol, polypropylene glycol, polybutylene glycol, poly(tetramethylene ether)glycol, hydroxy-terminated poly(butadiene), hydroxy-terminated polyesters and hydroxy-terminated alkyds. When a polyhydric alcohol is used as the initiator, the polyether polymer typically grows from the hydroxy groups of the initiator and the subsequently obtained polyether is a polyether polyol. Diols having 2 to 6 carbon atoms constitute the preferred polyhydric alcohol initiators. Water may also be used as the initiator.
As mentioned above, the residues of the initiator compounds may constitute a minor or major portion of the molecular weight of the polyether alcohols of the invention. For example, if a polymeric initiator, e.g. a hydroxyl-terminated polyoxyalkylene polymer, is employed and the number of repeat units of 3,4-epoxy-1-butene residue is relatively low, the initiator residue content of the polyether alcohol may be greater than 90 weight percent. On the other hand, if the initiator employed is a low molecular weight compound such as methanol or water, the initiator residue may constitute as low as one weight percent or less of the polyether alcohol. The EpB polyether alcohols typically comprise at least 20 weight percent, preferably at least 30 weight percent, 3,4-epoxy-1-butene residues. When the polyether alcohol constitutes the main film-former of the coating composition, the ratio of 3,4-epoxy-1-butene to organic initiator used in the reaction is preferably higher thus producing a higher molecular weight, higher viscosity polyether alcohol. When the polyether alcohol is co-cured with another curable resin, the molar ratio of 3,4-epoxy-1-butene to organic initiator in the EpB polyether alcohol can be as low as about 1.0. Preferably the ratio of 3,4-epoxy-1-butene to initiator is from about 1 to about 70. More preferably the ratio is within the range of about 2-60 and most preferably it is within the range of from about 5-30.
The 3,4-epoxy-1-butene may be reacted with a saturated oxirane compound to dilute the 3,4-epoxy-1-butene in order to control the level of unsaturation of the EpB polyether alcohol. Thus another embodiment of the invention provides a polyether alcohol which is a reaction product of (i) 3,4-epoxy-1-butene, (ii) a saturated oxirane compound, and an (iii) an initiator selected from the group consisting of water and an alcohol. The EpB polyether alcohol comprises n units of residue (I) and m units of residue (II) shown above, wherein the sum of (n+m) in the EpB polyether alcohols is a value in the range of about 2 to 70 and n/(n+m) is a value in the range of about 0.70 to 0.95. These EpB polyether alcohols are also oxidatively curable and may be used in oxidatively curable coating compositions either as the main film-former or as a reactive diluent for another curable resin.
Accordingly, yet another embodiment of the invention provides an oxidatively curable coating composition which comprises about (a) 5-100 weight % of an EpB polyether alcohol which is the reaction product of 3,4-epoxy-1-butene, a saturated oxirane compound and optionally an initiator, (b) about 0-95 weight % of a curable resin, (c) about 0-40 weight % of an organic solvent, and (d) a catalytic amount of a metal drier.
Examples of saturated oxiranes which may be reacted with 3,4-epoxy-1-butene include, but are not limited to alkyl epoxides having from 2 to 26 carbon atoms such as ethylene oxide, propylene oxide, butylene oxide, butyl ethylene oxide, hexyl-ethylene oxide, tetramethyl-ethylene oxide, cyclohexene epoxide, 3,4-dichloro-1,2-epoxybutane, and 3,4-dibromo-1,2-epoxybutane. Additionally, styrene oxide, and glycidyl ethers such as bisphenol A diglycidyl ether, butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, glycidyl acetate, glycidyl propionate, glycidyl 2-ethylhexanoate, and glycidyl neodecanoate may also be used.
Preferably the molar ratio of the saturated oxirane compound to the 3,4-epoxy-1-butene is from about 0.05 to 10 and the molar ratio of the sum the moles of 3,4-epoxy-1-butene and saturated oxirane divided by the moles of initiator [(i+ii)/iii] is from about 1-30.
The 3,4-epoxy-1-butene may also be copolymerized with another unsaturated oxirane such as allyl glycidyl ether, isoprene monoepoxide, vinyl cyclohexene epoxide, limonene monoepoxide, 1,2-epoxy-5-hexene, etc.
To prepare the EpB polyether alcohols, 3,4-epoxy-1-butene is polymerized via a ring-opening reaction which may be initiated with water or an alcohol. The ring-opening reaction may be acid catalyzed as disclosed in U.S. Pat. Nos. 5,393,867, 5,434,314, and 5,536,882, all of which are incorporated by reference herein in their entirety. Alternatively, the polyether alcohols may be polymerized in the presence of a base catalyst as disclosed in U.S. Pat. No. 5,200,437, incorporated by reference herein in its entirety. As discussed above, the EpB polyether alcohols contain branched repeating units (I) as well as linear repeating units (II). These repeating units (I) and (II) result from the ring opening of the 3,4-epoxy-1-butene. The EpB polyether alcohols contain n units of (I) and m units of (II) which have the structures: 
In the EpB polyether alcohols, the total value of (n+m) is 1 to 70 and n/(n+m) is a value in the range of about 0.70 to 1.00. Preferably, the sum of (n+m) is a value in the range of about 2 to 70 and the ratio of n/(n+m) is a value in the range of between about 0.70 to 0.95. Acid catalyzed reactions generally produce polyether alcohols with a higher ratio of residue (II) to residue (I) than base catalyzed reactions, generally in the range of 0.7 to 0.95. In general, base catalyzed reactions produce polyether alcohols with an n/(n+m) in the range of about 0.96-1.00. However, when an unsaturated alcohol such as 2-butene-1,4-diol, is used as the initiator, it is possible to get ratios of n/(n+m) of less than 0.96.
The acidic catalysts which may be used to prepare the EpB polyether alcohols include strong acids which are typically Bronsted acids such as sulfuric acid; perchloric acid; fluoroboric acid; strongly acidic ion exchange resins, e.g., Amberlyst(copyright) resins (sulfonated polystyrene); fluorosulfonic acids such as perfluoro-alkanesulfonic acids containing up to about 6 carbon atoms, e.g., trifluoromethanesulfonic acid, fluorosulfonic acid, and perfluorosulfonic acid polymers, e.g., Nafion(copyright) (Dupont) resins. The acid catalyst may also be a Lewis acid, such as boron trifluoride, boron trifluoride etherate, boron trifluoride tetrahydrofuran complex, aluminum chloride, zinc chloride, tin tetrachloride, etc. The preferred catalysts, are boron trifluoride etherate, and Nafion NR-50(copyright) perfluorosulfonic acidic resin, which has been cryogenically ground to 60 to 100 mesh (particles having an average diameter of 170 to 250 microns). The amount of the acidic catalyst which may be used can vary substantially depending, for example, on process conditions and the particular acid employed. For batch operations, the amount of catalyst used typically is in the range of about 0.5 to 20 mole percent based on the equivalents of initiator.
As mentioned above, the EpB polyether alcohols may also be prepared by a ring-opening reaction of the 3,4-epoxy-1-butene which is initiated with water or an alcohol and catalyzed by a base catalyst. Suitable base catalysts include, for example, sodium or potassium metal, sodium or potassium hydroxide, alkoxide, hydride, phenoxide, or an alkaline earth metal hydroxide or alkoxide. The catalyst is preferably employed in a concentration of between about 0.1 and about 5 wt. %, more preferably between about 0.4 and about 1 wt. %, based on total reactants.
The ring-opening reaction is typically conducted in the absence of solvent. However, in instances where the mixture of reactants provides a liquid having a viscosity such that good agitation becomes difficult, up to about 90 wt. % of an inert solvent may be added. Examples of such inert solvents for the acid-catalyzed polymerization include hydrocarbons, such as toluene, xylene isomers, benzene, and heptane; and chlorinated hydrocarbons, such as methylene chloride, chloroform, chlorobenzene and dichlorobenezene isomers. Examples of inert solvents which may be used for the base-catalyzed polymerization include hydrocarbons, such as toluene, xylene isomers, benzene, and heptane; chlorinated hydrocarbons, such as chlorobenzene and dichlorobenzene isomers; cyclic or acyclic ethers, such as methyl t-butyl ether, diethyl ether, dibutyl ether, diisopropyl ether, 1,2-dimethoxyethane, bis(2-methoxyethyl) ether, tetrahydrofuran, and amides such as N-methyl-pyrrolidone, N,N-dimethylformamide, N-ethyl-pyrrolidone; and nitrites such as benzonitrile.
The present reaction is effected in the liquid phase by agitating the reactants under a blanket of inert gas, e.g. nitrogen, argon, etc., at a temperature within the range of between about 40xc2x0 C. to about 150xc2x0 C., depending upon the choice of initiator, solvent, and catalyst, and under from about atmospheric pressure up to about 1,000 psi when volatile reactants or solvents are employed in the reaction mixture. The reaction takes place over a period of from about 1 to 48 hours. Preferred base-catalyzed conditions include a temperature of between about 100xc2x0 C. and about 130xc2x0 C. at slightly above atmospheric pressure for a period of from about 2 to 20 hours. Preferred acid-catalyzed conditions include a temperature of between about 30xc2x0 C. and about 70xc2x0 C. under atmospheric pressure for a period of from about 2 to 10 hours.
Examples of EpB polyether alcohol preparation are illustrated in the reaction schemes below. EpB polyether alcohol 1 was obtained by removing the low boilers from the reaction products of methanol and an excess of 3,4-epoxy-1-butene. EpB polyether alcohol 2 was obtained similarly from the reaction of 3,4-epoxy-1-butene and ethylene glycol, and it contained about 5 repeat units. EpB polyether alcohol 3 was also prepared from 3,4-epoxy-1-butene and ethylene glycol, but it contained about 8 repeat units. The polyether alcohols of the invention preferably contain from 1 to about 10 hydroxyl groups. Detailed descriptions of preparations of the EpB polyether alcohols are described in Examples 1-13 and 15 below. For clarity of illustration the figure depicts blocks of residues (II) and (II), however as discussed below, the EpB polyether alcohol has a random distribution of residues (I) and (II). 
As mentioned above, the 3,4-epoxy-1-butene may be diluted by reacting it with a saturated oxirane compound and the initiator, to control the unsaturation of the EpB polyether alcohol. The reaction products may be random or block copolymers of the 3,4-epoxy-1-butene and the saturated oxirane compound. Examples of EpB polyether alcohol preparation via this route are illustrated in the reaction schemes below. Detailed descriptions of preparations of the EpB polyether alcohols containing a saturated oxirane are described in Examples 8 and 9 below. The EpB polyether alcohols produced by this reaction are also useful in oxidatively curable coating compositions. 
Where R1 is the terminal residue of the alcohol or a hydrogen atom and R is a saturated hydrocarbon group.
Accordingly, another embodiment of the invention provides for an EpB polyether alcohol which is a block copolymer comprised of a reaction product of (a) 3,4-epoxy-1-butene, and (b) a saturated oxirane compound and (c) an initiator selected from the group consisting of water and an alcohol. In this embodiment, a saturated oxirane polymer such as polyethylene glycol may function as the initiator, see e.g., Example 9. The EpB polyether alcohol comprises n units of residue (I) and m units of residue (II) having the structures: 
wherein the total value of (n+m) is 1 to 70 and n/(n+m) is a value in the range of 0.70 to 1.00. These EpB polyether alcohols can be block or random copolymers of the 3,4-epoxy-1-butene and the saturated oxirane. The block copolymers of 3,4-epoxy-1-butene and ethylene oxide are particularly useful as surfactants in, for example, oxidatively curable coating compositions as they are water-soluble but still retain their oxidative curing property.
As discussed above a coating composition of the invention may contain about (a) 5-100 weight % of the oxidatively curable EpB polyether alcohol, (b) about 0-95 weight % of a curable resin, (c) about 0-40 weight % of an organic solvent and (d) a catalytic amount of a metal drier. More preferably, the composition comprises about 10-50 weight % of the polyether alcohol (a), about 50-80 weight % of the curable resin (b) and about 0-30 weight % of the organic solvent (c). Most preferably the composition comprises about 15-30 weight % of the polyether alcohol (a), about 60-75 weight % of the curable resin (b), and about 0-20 weight % of the organic solvent (c).
The curable resins (b) useful in the oxidatively curable coating compositions are those which are oxidatively curable themselves and those which are co-curable oxidatively with the polyether alcohol. Preferably the curable resin (b) contains carbon-carbon-unsaturation. Examples of suitable curable resins containing carbon-carbon unsaturation include acrylamide functional resins, alkyd resins, unsaturated epoxy resins, unsaturated urethane resins, unsaturated polyester resins, modified polyester resins containing unsaturation, polybutadiene resins, acrylate functional oligomers, e.g., pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate esters and diethylene glycol diacrylate, acrylate functional polymers, and acrylic latex resins. Other suitable unsaturation sites on the curable resins include maleate, fumarate, and itaconate esters and acid esters.
For example, EpB polyether alcohols may be mixed or otherwise combined with acrylic latexes which have been functionalized with groups that are radically polymerizable, such as allyl ester, allyl ether, acrylate ester, methacrylate ester, methacrylamide, terminal olefin, maleate ester, and the like. The latexes may also contain groups that promote chain transfer and grafting such as acetoacetate esters and their enamine reaction products with amines, mercaptans, substituted alcohol or ether groups (such as polymer-OCHxe2x80x94(CH3)2 or polymer-OCH2CH(CH3)OH). These materials (functional latex and EpB polyether alcohol) may be combined, optionally with the aid of a surfactant, to form stable blends which form films on evaporation of water and/or solvents. The films cure oxidatively and are solvent resistant due to the cross-linking which occurs during curing.
The organic solvents (c) which may be used in the oxidatively curable coating compositions include inert solvents such as hydrocarbons, chlorinated hydrocarbons, cyclic or acyclic ethers, alcohols, esters, ketones, glycol ethers and acetates and the like. Examples of such solvents include mineral spirits, hetane, hexane, benzene, toluene, xylene isomers, methylene chloride, chloroform, tetrahydrofuran, methoxypropanol, butoxyethanol, hexyl ether of diethylene glycol, Texanol(copyright), methyl n-amyl ketone, methyl isobutyl ketone, n-butyl acetate, isopropyl acetate, n-butanol, 2-butanol, 2-ethylhexanol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monobutyl ether and the like.
Metal driers may be used to accelerate the curing process. The drier may be any polyvalent metal-containing complex or salt which catalyzes the oxidative curing of the coating composition. Examples of metal driers (d) which may be used include metal carboxylates which are the reaction products of metals and organic acids. Such metals include cobalt, zirconium, calcium, manganese, rare earth metals, e.g., lanthanum and cerium, aluminum, zinc, iron and mixtures thereof. Preferred driers are mixtures of the Zirconium Hexcem(copyright), Cobalt HydrocureII(copyright), Cobalt Hexcem(copyright) and Calcium Hydrocem(copyright) driers which are available from OMG America, Cleveland, Ohio. The drier is typically present in an amount of about 1.0 to about 5% metal content by weight of the coating composition.
According to the invention, EpB polyether alcohols may also be copolymerized with a low molecular weight compound to provide EpB polyether alcohol derivatives with enhanced film-forming properties and increased molecular weight while still retaining oxidative curing properties. For example, EpB polyether alcohol may be reacted with di-isocyanates to provide polymers which cure oxidatively, and add additional coating properties such as flexibility, hardness and solvent resistance that are contributed by the resulting urethane functionality and increased molecular weight. Additional low molecular weight compounds which may be reacted with the EpB polyether alcohols include di-epoxides, tri-epoxides, di-esters, carbonates, mono-isocyanates, polyisocyanates, and the like. Since the EpB polyether alcohols may have from 1 to about 10 hydroxyl groups per molecule, one skilled in the art may manipulate these EpB polyether alcohols to produce useful polymers of increased molecular weight without producing a significant gel content which would be less useful for coatings.
The oxidatively curabable coatings may contain one or more conventional additives. Such additives include but are not limited to, leveling, rheology, and flow control agents such as silicones, fluorocarbons, urethanes, or cellulosics; extenders; reactive coalescing aids such as those described in U.S. Pat. No. 5,349,026; flatting agents; pigment wetting and dispersing agents and surfactants; ultra-violet (UV) absorbers; WV light stabilizers; tinting pigments; extenders; defoaming and antifoaming agents; anti-settling, anti-sag and bodying agents; anti-skinning agents; anti-flooding and anti-floating agents, fungicides and mildewcides; corrosion inhibitors; thickening agents; plasticizers; reactive plasticizers; curing agents; or coalescing agents. Specific examples of such additives may be found in Raw Materials Index, published by the National Paint and Coatings Association, 1500 Rhode Island Avenue, NW, Washington, D.C. 20005.
The oxidatively curable coatings of the invention are useful in a variety of coating compositions such as architectural coatings, maintenance coatings, industrial coatings, automotive coatings, textile coatings, inks, adhesives, and coatings for glass, metal, paper, wood, and plastics. The coating compositions may be clear or pigmented.
The coating composition of the invention may be applied to a variety of surfaces, substrates, or articles, e.g., paper, plastic, steel, aluminum or other metals, wood, gypsum board, galvanized sheeting (either primed or unprimed), concrete, nonwoven or woven fabrics, glass, ceramics, glazed or unglazed tiles, plaster, stucco and roofing substrates such as asphaltic coatings, roofing felts, synthetic polymer membranes, and foamed polyurethane insulation; or to previously painted, primed or undercoated, worn or weathered substrates.
The coating compositions of the invention may be applied to appropriate substrates as thin films by a variety of techniques known in the art. For example, a coating composition may be applied by roll coating, dip coating, spray coating, e.g., by air-assisted spray or airless spray, trowels, paint brush, flexographic, lithographic and offset-web printing processes or the like.
In general, the films may be cured by heating, e.g., in an air oven or by IR lamps, or by air drying. Exposing the film to a temperature of up to about 150xc2x0 C., preferably to a temperature of between about 50 to 120xc2x0 C., accelerates the curing time. Advantageously, the films cure to form a hard, solvent resistant coating. Accordingly, another embodiment of the invention relates to a cured film of the EpB polyether alcohol coating composition.
This invention can be further illustrated by the following examples of preferred embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.